Stack of three bars

Peanut Butter Billionaire’s Shortbread

  • Author: closeenoughcook
  • Prep Time: 45
  • Cook Time: 45
  • Total Time: 1 hour 30 minutes
  • Yield: approx. 20-24 bars


This recipe takes millionaire’s shortbread and turns it into billionaire’s shortbread with the addition of peanut butter.  It combines the best parts of a Twix and a Snickers and turns them into homemade deliciousness.  Eat just one and you’ll be craving more for days. Don’t say I didn’t warn you . . .

Adapted from The Perfect Cookie by America’s Test Kitchen



Shortbread Crust

2 1/2 cups all-purpose flour

1/2 cup sugar

3/4 tsp salt

2 sticks unsalted butter, melted  

Caramel Layer

1 (14 oz. can) sweetened condensed milk

1 cup packed light brown sugar

1/2 cup heavy cream

1/2 cup corn syrup

1 stick unsalted butter

1/2 tsp. salt

Peanut Butter Layer

6 tbsp packed light brown sugar

2 cups confectioner’s sugar

6 tbsp unsalted butter softened

1 1/3 cup creamy peanut butter

Chocolate Layer  

8 ounces semisweet chocolate chips

1/2 cup peanuts, rough chopped for garnish (optional)


  1. Preheat oven to 350 degrees. 
  2. Make a foil sling in a 13 inch by 9 inch baking dish by placing one piece of tin foil length-wise in the baking pan, making sure to use enough foil that it hangs over the sides of the dish, and a piece of tin foil width-wise in the dish, again making sure to use enough so that it hangs over the sides.  Flatten foil against bottoms and sides as well as in corners to make the foil as flush with the dish as possible.
  3. Combine flour, sugar, and salt in a large bowl.  Stir in melted butter until fully incorporated.  
  4. Place ball of dough in dish and using hands push the dough outwards until the bottom of the dish is fully covered.  As much as possible try to have the shortbread layer be an even thickness.  
  5. Dock the shortbread using a fork at 1-inch intervals.*
  6. Back shortbread approximately 25-30 minutes or until crust is beginning to brown and is firm to the touch. 
  7. Allow shortbread to rest until cool to the touch. 
  8. While shortbread is baking, begin to make the caramel layer by stirring the condensed milk, brown sugar, butter, cream and corn syrup together in a large pot over medium heat.
  9. Cook, stirring frequently, until mixture is between 236 and 239 degrees (approximately 20 minutes).**
  10. When caramel is done cooking, pour over the top of the shortbread and put pan in refrigerator until caramel is cool to the touch. 
  11. While caramel is cooling make the peanut butter layer by combining all ingredients in a medium bowl. 
  12. When caramel has completely cooled, cover with peanut butter layer by dropping spoonfuls of the peanut butter mixture over top the caramel and gently smoothing with an off-set spatula.***  
  13. For the chocolate layer, place chips in a small bowl and microwave, stopping every 15 seconds to stir, until chocolate is almost completely melted (approx. 1 minute).  Take care not to overheat the chocolate.  
  14. Stir chocolate until completely smooth and then pour over the peanut butter layer.  Spread chocolate into an even layer using an offset spatula.  Work quickly as chocolate tends to reharden relatively fast.
  15. Place shortbread in refrigerator for at least 30 minutes. 
  16. If using, warm reserved peanut butter layer and microwave in 10 second intervals until mixture is pourable but runny.  
  17. Using a spoon drizzle warm peanut butter mixture over top of the chocolate layer and garnish with chopped peanuts.  

*”Docking” means to poke holes in a pastry crust so as to allow steam to escape during cooking thus preventing the crust from puffing up.  

** If you don’t have a thermometer handy, you can tell when the caramel is ready by using the cold water test. 236-239 degrees is the “soft ball stage” of candy making which means that when a you drop a bit of the mixture into a glass of cold water it will form a soft malleable ball.  Once the caramel reaches this point it’s done cooking.  Here’s some more information on the cold water test if needed.

***If planning to garnish the top of the bars with peanut butter sauce, reserve approximate three tablespoons of mixture and set aside.